A semiconductor device is arranged by having a shield/planarization portion including a silicided active region formed on the main surface of a semiconductor substrate and a non-active region provided by device-isolation on the surface, and a metal layer such as a pad, wiring layer or inductor having a predetermined pattern, formed on an interlayer insulation film formed on the above shield/planarization portion. Just under the metal layer is disposed the shield/planarization portion in which the area ratio of the active region to the non-active region is given in a predetermined proportion and the active region is electrically grounded.